Flexible bag for vacuum sealing



May 12, 1953 c. J. JESNIG 2,633,263

FLEXIBLE BAG FOR VACUUM SEALING Filed May 20, 1949 INVENTOR. Charles J.Jeshig Z wpqg Patented May 12, 1953 Charles J. Jesnig, Newto wn Square,Pa., assignor to Duo-Vent Vacuum Closure Company, Philadelphia, Pa., acorporation of Pennsylvania.

Application May 20, 1949,.Serial No. 94,405

4 Claims.

This invention relates to vacuum packed flexible containers and to amethod of packaging same.

With the development of the arts of packaging and preserving there hasarisen what is by now a long-standing problem in the art of packagesformed of flexible materials, in which articles, such as food stuffs,can be placed, but so made that the entire container can be evacuated soas to maintain the contents under a high, degree of vacuum for longperiods. The commercial efforts toward this end in the past have beenboth expensive and uncertain and therefore of limited application. Thisis for the reason that the method of packaging used first evacuates thebag containing the packaged materials, then, and second, whileattempting to maintain the vacuum seals the previously open end of thebag or container. This has resulted in improper or inadequate degrees ofevacuation, in waste of the material of the bags, through tearing offthe excess necessary for the evacuation step, and,

' in frequent cases, in improper sealing. This is for the reason thatwith certain types of packaged materials of the powdered or like sort ofmaterials to be packaged there are frequently present small powderedparticles light enough to move on a current or stream of air. With thewithdrawal of the entrapped air through the open end of the bag orcontainer, these small particles moving with the withdrawing air,frequently partially ionized by friction, cling to the walls of thecontainer, so that when the ultimate heat or like sealing occurs, theparticles between the walls at the joint or connection preclude anactual tight or permanent seal, so that air seepage is permitted throughthe supposedly sealed bag end. Obviously this soon vents the vacuum andthe packaging is improper, which is disastrous if the material issupposed to be maintained under vacuum.

Another disadvantage of the previous attempts at filling, evacuating andsealing filled flexible containers lies in the fact that with theprocedures followed it is impossible to obtain more thana certain degreeof evacuation, less than complete, so that there remains a certainvolume of air, however thin, in effect. Or the products packaged may besuch as a certain period which partially or completely fills thecontainer. With incidence to extremes of temperature, or, and more highaltitude attainment through air freight or the like, the relativeincrease of internal pressure by the expansion of the entrapped gas orto emit a gas duringcommonly, with air, or by the decrease of density ofthe external atmospheric air, in many cases increases the internalpressure to such degree as to cause bursting of the container, withconsequent spoilage of the contents.

By applicants method a bag or container is provided of suitable flexibleor film material, such as one of the many available plastic sheetmaterials, open on one end- A performed valve unit is heat sealed oradhesively mounted on a desired area of one wall of the container. Theopen bag is then filled with the desired material to be packaged, andthe range of such materials seems infinite, excluding only liquids, andthe open end of the bag is then sealed, as by heat or adhesives or both.The materials are thus disposed in asealed container containingentrapped air. Then the bag is exposed to an evacuated atmosphere,either enclosing the whole bag, as when a plurality thereof are to beevacuated simultaneously in a chamber, or selectively adjacent to thepreformed valve unit of a given bag by-a suitable manipulatible nozzlemounted thereover.

It is among the objects of this invention: to provide a cheap andeconomical flexible bag for the preservation under vacuum of anycontents placed in the bag; toprovide a sheet material with a vacuumsealing valve element; to provide a combination of a valve with aflexible container which can be simultaneously coupled together andplaced under venting relations so as to facilitate vacuum sealing thecontainer; to provide a-plastic sheet with a valve seat of relatedmaterial arranged for mutual heat sealing into a single unit; to improvemethods of packaging material in fiexible'containers under vacuum; toprovide a bag or flexible container with a-sealed in valve unit assemblywhile providing an open mouth for the insertion of materials to bepackaged and which is susceptible to sealing at the open mouth withoutregard to the internal pressures in the container, and which isthereafter subjected'toexposure to differential internal and externalpressures forsealing; to minimize thelosses formerly due to impropersealing of flexible containers arising from particles drawn out throughthe mouth of the container being disposed between the contiguousportions of the bag at the sealing line; to provide a flexible containeror bag for vacuum packaging contents thereof, with valve means havingthe property of venting internal relative pressures whenever thedifferential between internal and external pressures becomesappreciable, whereby after sealing the entrapped air can be evacuatedfrom the bag or flexible container which snaps shut and prevents theingress of external atmosphere, and whereby any gases produced by orliberated from the contents of the bag can be safely vented withoutpermitting external atmosphere to enter, and furthermore whereby anyentrapped air or gas in the sealed bag or container, when expandingbecause of decrease of external pressures can vent the excess volume ofgas from the bag to prevent rupture thereof under such internalpressure; toprovide' a method and means for packaging articles inflexible containers with an inserted entrapped gas content in thecontainers in contact with the contents of the container; to provide aflexible container'with a preformed valve unit assembly in adherentrelation to the walls of the bag so as to preclude adverse contact ofthe goods in the container from. the valve unit; and" other objects andadvantages will become more apparent as" the description proceeds.

In the accompanying drawings forming part of this description:

Fig. 1 represents a fragmentary section, on an enlarged scale, of aportion" of the flexible sheet forming the container with a valveassembly heat-sealed thereto, and showing the opening formed in thesheet in. communication with the valve for venting the air from withinthe bag when the latter has been filled and completed.

Fig. 2 represents a fragmentary bottom plan of the valve unit offFig. 1;

Fig. 3 represents a bag formed according to the invention, containingarticles to be preserved, after the bag has been evacuated tosubstantially eliminate internal air therefrom;

Fig. 4 represents a fragmentary plan of a bag or flexible container withthe valve'unit sealed partially away from the goods-receiving portion ofthe container so that venting through the valve can occur, while contactof the bag contents with the valve unit is substantially precluded;

By the. invention herein, sheets or films of'airtight. plastic material,such as the products known in the trade as Pl'iofilm, Saran and thelike,are provided, either as single thicknesses; or pluralities. thereof in alaminated sheet, which are preferably transparent, tough, impervious toair penetration where required, non-toxic when u used with food. stuffs,all designated herein as sheets. There are many such plastic filmmaterials which are now or will become available for use in thisinvention. For purposes of description, it will be. assumed that. thepreferred material is the Dow Chemical Companys product Saran. A sheetH! of such film is provided, of any desired size, arranged. either as atube for sealing. of the endsto form a bag or flexible container, or forfolding upon itself with heat-sealed or adhesively sealed edges to forman openmouthed flexible bag or receptacle, or for'association with asimilar or related sheet for heat or related adhesive sealing on threesides to form such open-mouthedv flexible container. -A valve unitassembly is provided, formed of a valve seat element, and a resilient,illustratively rubber, valve button or insert, operativ'ely associatedtherewith. The valve seat is formed of material capable of heat sealingor adhesiveattachment to the sheet Ill. With polymerized materials itwill be evident that solvents can beused in forming bodily rnergencebetween the plastic components. Usually the valve seat will be of thesame plastic material as-the sheet; Illustrativehooking portion of. thevalve button.

1y then, the valve seat unit is also formed of Saran having a chemicalcomposition identical with the sheet if and the valve seat unit orelement is molded into the shape to be recited. The molded valve seatelement molded from Saran is not rigid but is capable of re rains:flexure, and is normally of suiilcient this to be generallyself-sustaining. The in valve seat unit, except possibly in the so:inner valve seat portion where rigidity may be important, may be capableof partial fi. y ieldmg under. certain minor stresses. The plastic valveunit as molded comprises an upper annal ar fiange H', of sufficient areato insure firm sealing; under heat or solvent with the surface of thesheet it to which it is juxtapo d in assembly; The iiange isrestrainedly fie? is so as to conform without unsealing to the shapeassumed by the contiguous areas of the sheet. as the latter conforms topackaged contents in vacuum'zi: flange ii at substantiallye right angleinto a generally cyliudrical well 12 of such axial length as toestablien-adequate clearance: between the top of the valve buttonto' bedescribed, and the inner surl ace 0t the juxtaposed. portion of sheetit, and is" of. such diametri'c as to receive and permit flexing of theresilient flange of the valve button to: be described. The Well isformed of a wall if having inner wall surface :2 and outer surface andinternally terminates in the generally horizontal. valve seat It, whichusually and preferably inch-ides an annular crest l t, to facilitatesealing between the flexible rriernber' of the button to be describedand the valve; seat. The crest Hi, if provided, or the valvess's'at i3,merges more or less arcuately into the'g'maerally concentric axial valveguid surface" [5,. of relativeiy short axial extent, pre erably,although obviously not essentially, parallel to, andgzstaggeredrinwardly of, the wall i2. Valve seat i3, crest it, and valve guide 55 re surfaces of: a transverse or horizontal wall 52, terminating in alower horizontal anchoring siurface ti. valveseat: unit is completed bya short" cylindrical guard ii, generally parallel with the wall'fiiofthe well it, extending downwardly from transverse wall 8' externallyradially inwardly staggered from the external surface 25] a or.the'well', in the external guard surface 2!.

The: guard extension ll has an internal surface 22. of" greater diameterthan guide it so that it is radially outwardly. spaced from the surfacetil of: the. guide, to" form a clearance for the Apertur'es are formedin the guard extending radially completely tlierethrough below thesurface It ofrthe: valve seat as shown at 3b in order to adto the lowersurface of the valve seat, even" if (the end-surface 23 of. the guard iishould happen to be sealed oii by the contents of the ultimate bag.desired means can be used to-prevent entryof packaged material into theguard emension. i"? toa degree permitting abutmerit; against the end ofthe button. Such means includes making the guardil longer, or attaching;aguarding cap 3? or insuring that the end. thereof is; only abutted by acomplementa-l sheet" portion of. the bag, asby enclosing the flange'in'a heat sealed incomplete ring joinmg'opposite contigu'ousgsurfaces orsheets of the bag together; to enciose the valve unit thereby, as shownin; Fig. 4. While these apertures 3t bedrill'ed or otherwise formed sothat they do not: interrupt the endsurface 2:3- as indicated anti), forease offormation" in molding the apertures such venting aperturespreferably comprises one or more axial through slots 36, extending partor the full length of the guard l1. Preferably, there are three suchslots 36, in angular substantially equal spacing as shown. If desired,in the molding of the valve seat unit, small slits or slots 3| canbeformed through the valve seat extending from the surface Hi to thesurface 55 to permit or facilitate venting, to be described.

For operative association with the molded Saran valve seat as"described, a single uni tary resilient valve button is provided of softrubber or "the like, comprising a stem 24, which may be solid or hollow,and of such diameter as to enter and contract within the guide l5. Stem24 loads at the top into a flexible flange 25 of such diameter as tooverlie the valve'se'at l3, by extending radially outwardly beyond thecrest it substantiallyput of frictional engagement with well l2. Theflexible flange 25 is preferably reinforced toward the center by thesmaller flexible flange 2.5, connected thereto by a short thick shank 21and so designed and located as to reinforce the center of the valveunit, to preclude it from being drawn inwardly into the container underhigh differential internal .and'external pressures. The valve stem 24 atthe'lower end terminates in the laterally extending flanged or hookedelement 28, arranged to underlie the surface l6 of the valve seat toprevent the valve button from being forced out of the valve guide byinternal pressures when the outer members of the valve are subjected tovacuumconditions. The resilient unitary valve button at the lower end istapered as at 28' to facilitate axial insertion into the valve seatunit. Preferably the stem 24, be-

tween the flanges 25 and 28 is predeterminedly a -little shorter thanthe axial length of the valve guide It, sothat when anchored, thesealing flangezfi is biased toward and against the valve seat 13 byslight axial extension of stem 24. The relation of the axial length ofthe stem 24 to the valve guide 15, is predetermined to establish thedifferential between internal and external pressures at which the valvewill unseat for venting purposes. To assist in venting, the uppersurfaceof hook portion 28 can be provided with one or more shallow grooves orchannelsr32 ofsuch length as to conduct venting air from the outersurface of hook flange 28 to delivery externally of stem 24.Alternatively or additionally, an axially extending eccentricallydisposed slot 35 is formed extending through anchoring portion 28 andleading at least part way up stem 24. Slot 35 may simply axially pierceflange 28 or continue radially to the outer periphery thereof.

In assembling the flexible container, the valve button is first insertedaxially to anchored relation in the valve seat, preferably, as noted,under slight axial tension on stem 24. The assembly is then placed underthe sheet of material ID in operative parallel contacting relationbetween elements of a heat or other sealing device. This is not shown,but preferably is of the Well known electronic type. Simultaneously,preferably, but not essentially, one or more heated or cold needles orother piercing devices (not shown) are brought into contact with thesheet I0 in general registration with the well l2, to form minuteapertures 29, as the only surface interruption in the sheet adjacent tothe valve. A1-

ternatively' according to the selected materials suitable adhesives suchas partial solvents may be applied to the flange H which is held underpressure against sheet Hl'until sealing bonding is secured.

The sheet Hl thencarries, as a substantially integral part, the valveassembly, and from this sheet, in accordance with the well-known methodsvof procedure with such materials a bag is formed,'open at one edgethereof. Let it be assumed, in Fig. 3, that the open endis at the righthand end of the bag, as shown in dotted lines. The thus prepared bag isultimately filled through the open mouth and the open mouth is then heatsealed or adhesively bonded as shown in full lines at the right of Fig.3. The bag then contains entrapped air. Illustratively, the con tents ofthe bag can be any sort of food stuffs, such as dried fruits, cereals,meats, such as beefsteaks, whole carcasses of fowl, or the like. As soonas desired after the filled bag has been completed by the final edgeheat or other sealit is exposed tovaouumizing. This can be done in smallestablishments by small pumps having a sucking intake large enough torest over and upon the sheet [0 superposed over the valve assembly, soas to 'pull a vacuum on the individual bags. In larger assembly plantspluralities of the filled containers are placed in large chambers atrandom and all are simultaneously evacuated by evacuating the chamberand holding the vacuum conditions long enough to evacuate the air fromall of the sealed containers.

When the evacuation of the filled sealed containers begins, there issubstantially atmospheric pressure within the bag, while at the aperture29, and therefore on the entire surface of flange 25, there is lessthan'atmospheric pressure. The higher internal pressure passes throughone or more of the venting passages to the space beside the stem 24under the flange 25, raising the latter slightly from the valve seatagainst the resilient bias of the short stem, to vent the internal airpressure in the bags. This venting continues as long as the differentialpressures on the opposite sides of the flange 25 are positive on theinterior of the container. as the internal and external pressures becomesubstantially identical, the flange 25 snaps down upon and against thevalve seat It, including the crest H3, if, as is preferred, such isused. The outer surface of sheet l0 adjacent to aperture 30 is thenexposed to atmospheric pressure, replacing the low pressure formerlyincident on the outer surface of the flange 25, and the flange 25 isforced by atmospheric pressure into tight sealing engagement against thevalve seat. The

vacuum thus created in the container maintains as long as the air isexcluded from passage any way through the sheet 10 into the interior ofthe bag formed thereof. If the material is airtight, such maintenance ofvacuum is a function of the completeness of the adhesive or heat sealingat the edges and between the flange H and sheet 10.

The advantages of the invention in cheapness, availability, maintenanceof high vacuum, with visibility of the contents, will be apparent, fromthe preceding description, but a further advantage attaches to theinvention depending somewhat upon the puncturability of the rubber valveunit. For this purpose, the valve is made hollow and the package is onein which an inert gas is to be brought into contact with the packagedgoods As soon 1 7 with-in the' flexible hag; Such gases are those"having:preservativefunctions or being, free: from an oxygen content; orotherwiseconducing to the preservation" o'f'the contents. With suchpackage, after filling the bags or containers and sealing oii the mouthsthereof, the packagesare exhausted of'air in: the manner described,utilizing the venting characteristics of the valve unit as before.latter as adegrec of: vacuum aspossihle is attained and helduntilfurther processing is desired, a; needle communicating with asource the replacement orinert orvapor' is inserted. through the rubbervalve unit into the i oi the flexible bag, and a charge of. such go.permitted to be drawn or is: forced into the bag withoutunscalingthevalve-fromthe plastic valve seat. The gasreplacementmaybe-a more partialsatisfying of the vacuum so that a. small residual gas supply exists ina still evacuated sealed. container; or the gas insert may be of acomplete atmosphere, so that'no actual vacuum the. container, but the:gas content is proper to safeguard the contents thereof. With a residualvacuum, the external pressure and the ruhheritself' bothconduce towardautomatic sealing. of the minute aperture formed. by the inserted andthen withdrasmrgag. needle.

Having thusdescribed my invention, I claim:

1.. A. flexible bag, comprising a; sheet of air-tight flexible materialtermed. into a portion at least of a bag, aprc-formedvalve unit sealedto an area of said. sheet andforming. with said area a boxlike.enclosure having appreciable depth relative to said sheet, said valveunit being of appreciably greater stiffness than the sheet to which itis attached an-dcomprisingawall surface defining a well partiallyclosedv at the inner end by a radially inwardly extending transversevalve seat having a generally. annular bore, the-axis of which issubstantially normal to said area, the outer end of said wall merginginto a mounting flange generally parallel to the transverse valve seatand extending radially outwardly of said wall and scalingly engaged withsaid area, with the portionof the area extending transversely across thewell forming an upper substantial closure of said enclosure, a resilientvalve element having a stem disposed in said here, a flexiblefiangemounted on the stem and overlying the valve seat within the well andforming with the stem and valve seat the inner substantial. closure ofthe enclosure spaced from and protected:v by said portion of the area,means for effectively anchoring the stem in the-bore inv spacedrelationtosaid flexible flange, firstmeans forming, a conduit for gases:from the interior of the bag to. the flexible flange radially inwardlyof the valve seat, second means forming. a conduit for ga es from theinterior of said enclosure to the exterior of the bag, said stemlinpositicn being under an initial tension tov he the flexible flangeagainst the valve seat predetermined to retain the sealing engagement ofthe flexible flange against said valve seat until awe determineddiiierential of gas pressures externally and internally of the bag.exist in such sense: as to permit the lifting of the flexible flangefrom the valve seat within the enclosure by flow through the: firstmeans to vent agiven excess internal pressure from the. bag;while-sealing said valve against said valve seat by pressure throughsaid second conduit means: when the difierential pressures externallyand internally of the bag are iii-the opposite sense.

2. flexihlebag as claimed. in claim 1, further charact sized by guar.-ng means preventing solid contents. iromblocking said first conduitmeans.

3. A flexihle bag asclaimed inclaim 1, further characterized by guardingmeans mounted on said Wall means preventing the bagv contents fromblocking said first conduit means.

a flexible bag as-claimed in claim 1,. further characterized by guardingmeans preventing the bag content from blocking said first conduit meansand comprising a compartmented portion of the bag containing saidpro-formed valve unit andseparated from the main portion of the bag by aperipheral area of sealing interconnection between opposite sheet areasof. the bag, having a connecting opening between the compartmented andmainportions of the bag forming part of the first conduit means.

CHARLES J. JESNIG.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 11,760,959 Ortner June 3, 1930 2,051.023 Bollard Aug. 18, 19362,173,571 Jesnig Sept 19, 1939 2,225,395 Young Dec, 17, 1940 2,241,943Berch May 13, 1941 2,398,477 Tucker Apr. 16, 1946 2,437,693. HartmanMar. 16, 1948

